This invention relates to a method for forming a contoured shape from a structural panel having a core faced with thermoplastic resin facings and a decorative film adhered to at least one facing.
Contoured sandwich panels for interiors of commercial aircraft have been made with facings composed with reinforcing fibers such as glass, carbon and p-aramid in thermoset resins like phenolics or epoxies and core materials of either honeycomb or foam. One technique to make contoured panels is to hand-lay up high performance pre-impregnated fabrics of phenolic or epoxy resin on either side of the core and form the assembly in a press operation. Under applied pressure the panel will be cured at temperatures between 125.degree. C. and 175.degree. C. for approximately 60 to 90 minutes. After the curing cycle the panels are placed on a cooling fixture to control the dimensional tolerances.
Most of the interior panels will then be decorated with decorative laminate films (DECLAM). DECLAM usually consists of the following components: clear TEDLAR.TM. polyvinyl fluoride (PVF) film layer for cleanability, silk screen inks for color design, opaque TEDLAR.TM. PVF film and an embossing layer for texture. Sometimes DECLAM includes a fiber reinforced layer for extra stability/strength. The processing temperature of decorative laminates should not exceed 100.degree. C.
Sometimes the DECLAM already incorporates adhesives to support the bonding to the panel. In most of the cases, an additional adhesive, like Bostic 7132, an isocynate activated adhesive, is sprayed onto the contoured panel before DECLAM is applied. The decorated laminate and the panel are placed in a vacuum forming tool before the whole package is rolled into an IR-oven for the final curing.
In comparison to thermosets, high performance thermoplastic matrix resin offer not only toughness and low flammability but also the possibility of melting and remelting the resin to accomplish the above-mentioned steps of forming and decorating in a one step process.